Treatment of simulated dilute Ni 2+ -containing wastewater by electrodeionisation with a bipolar membrane: Feasibility and current density distribution

A new configuration of electrodeionisation with a bipolar membrane (EDI-BP) with a segment electrode was proposed for the treatment of simulated dilute Ni2+-containing wastewater. The feasibility of EDI-BP was analysed and experimentally validated, and its current density distribution was studied simultaneously. The results showed that the stack allows the removal of nickel and sulphate anions nearly completely from the 30 mg/L Ni2+-containing wastewater. Under the experimental conditions, Ni2+-free diluate and a 27-times concentrated solution (820 ± 50 mg/L) can be obtained. The current density distribution of the stack is uneven, which is reflected by the following order of the resistances of the resins, Dowex 650C and Dowex 550A, with different ionic forms: Ni2+ N Na+ N H+ and SO2− N Cl− N OH−, respectively. 4 © 2014 Elsevier B.V. All rights reserved.

A new configuration of electrodeionisation with a bipolar membrane (EDI-BP) with a segment electrode was proposed for the treatment of simulated 30 mg/L Ni2 +-containing wastewater. After 98.5 h of experimental running at the current densities of 16.5 mA/cm2, the stack allows the removal of the nickel and sulphate anions nearly completely from the diluted solutions. In the process, the current density distribution of the stack along the flow direction of the feed was uneven; the current density initially increased and then stabilised from the inlet to the outlet of the feed Table 1 The resistance of the diluate compartment. Position Resin resistance (Ω) Solution resistance (Ω) The inlet of the first diluate compartment The outlet of the first diluate compartment The inlet of the second diluate compartment The outlet of the second diluate compartment The inlet of the first diluate compartment The inlet of the second diluate compartment 541.8 (Ni–CIX) ~8570 (0.051 mmol/L NiSO4) 49.2 (H–CIX) ~2530 (0.051 mmol/L H2SO4) 187.4 (SO4–AIX) ~2530 (0.051 mmol/L H2SO4) 58.3 (OH–AIX) N105 (H2O) 180.7 (Na–CIX) – 124.3 (Cl–AIX) – List of symbols The resistance was calculated by Eqs. 1 and 2, Ω; R0 Rx The resistance was detected by AC impedance spectroscopy, Ω; L0 The electrode distance of the conversion value, cm; Lx The electrode distance of detection value, cm; S0 The effective area of the electrode of the conversion value, cm2; Sx The effective area of the electrode of the detection value, 10 cm2;